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Changing MCU

Written by Administrator

After fumbling around with the USB port for a while I realized that it’s time to make a major step. I changed the CPU to a PIC18F67J60, which has an integrated Ethernet controller. So USB is history and future’s so bright that I gotta wear shades!

I ordered a development system from mikroElektronika last week and it came in today. It holds a PIC18F87J60 which is almost the same MCU I intend to use. The difference is 80 instead of 64pins, so it has a few more I/O ports and a second UART. I started to move the code to the new CPU and parts are already running. I got the display working today and the async serial to talk to the GPS mouse. Next step will be a serial EEPROM with SPI. (The old CPU had internal flash) Once this is doneI will look into the TCP/IP stack of Microchip and replace the USB communication by HTTP.

There is also a lot of redesign in hardware necessary. The new MCU needs 3.3V, so I will have to interface the 3.3V CPU with some 5V peripherals. I will look into porting all of the peripherals to 3V3 but I will have to do some serious thinking before I do that.

Anyhow the Ethernet beacon with the new MCU will bring along a lot of advantages: - A boot loader for in field upgrades of software - Remote management capabilities through HTTP. This means longer wires from your management console to the unit or - real remote management over the internet or WLAN connection - More flash memory to store different profiles